The Swiss Railways (abbreviated SBB for Schweizer Bundesbahnen) have awarded to Bombardier in May 2010 a contract for a new generation of 59 double deck inter-city trains – BOMBARDIER* TWINDEXX* - , which is the largest contract ever awarded in SBB‘s history.

In order to meet the requirements of SBB‘s future infrastructure development plan –aimed at shortening travel times, reducing environmental footprint and increasing passenger comfort- , these new generation of trains have been equipped with innovative mechatronic bogie technology for the compensation of the natural roll movement of the car body, integrated into the existing secondary suspension, developed by Bombardier and named BOMBARDIER* FLEXX* Tronic WAKO*.

Bombardier selected Liebherr as partner for the development of the actuators for the roll compensation and the lateral suspension system of the FLEXX Tronic WAKO.

FLEXX Tronic WAKO enables an increase of the train speed by up to 15% in curves, while enhancing travel comfort for passengers and reducing the track wear. Through the widened possible wheel angle and the enhanced steering of the gravity center/ bogie angle relationship, the car body is in a situation to tilt inward. The active electro-hydraulic technology developed by Liebherr makes it possible to neutralize the undesired rolling effects that are experienced by passengers in traditional trains when train speed is high.

In addition, the car body is actively damped thanks to the active electro-hydraulic technology, which brings an added contribution to the passengers’ comfort. The active roll monitoring allows a widened car cross-section as well, which in turn offers increased passenger comfort. The optimized system architecture based, among others, on new generation redundancy concepts, features very high level of reliability – up to 150 times higher than comparable traditional systems. Liebherr-Transportation Systems is responsible for the development and the supply of electro-hydraulic actuators. Such actuators are themselves self-contained hydraulic systems – assembled, filled up and tested under particularly severe conditions by Liebherr, which guarantees several years of efficient operation under the railways’ operating environment. The electro-hydraulic actuator features a „plug and play“ function, which allows the car builder to assemble the actuator on the bogie with just a cable wiring for power supply and electronic control, thus relieving him from having to install on-board hydraulic channels that have proven heavy, maintenance-intensive and installation time-consuming. The need for evacuating/ filling or re-filling the hydraulic system is cancelled, as is the risk for damaging the actuator caused by pollution of hydraulic fluid through inadequate installation or maintenance action.

This electro-hydraulic actuator from Liebherr-Transportation Systems is in principle maintenance-free. However, should there be anyway a need for a maintenance action, the actuator can be removed from the car very quickly, without any particular knowledge in hydraulic systems, which also prevents the long unplanned car out-of-service times.

This innovative system is controlled by a dedicated electronic unit, developed by Liebherr and directly integrated into the actuator, which is linked to the car’s main controller via CAN-Bus.

Liebherr’s scope of supplies for this system covers electro-hydraulic actuators with integrated power electronics for 59 trains. The parts will be delivered to Bombardier Bogies Site in Siegen, Germany.

The first series delivery is planned for January 2012. The deliveries will take place until 2017. With this innovative project Liebherr has proven once more that the company is a reliable partner for the railway industry with extensive experience in the field of integrated hydraulic systems.

*BOMBARDIER, FLEXX, TWINDEXX and WAKO are trademarks of Bombardier Inc. and its subsidiaries